A thermoplastic vulcanizate (“TPV”) can be used for weather seal application, for example, application in automobile sealing strip, due to its sealability, good surface appearance, durability, etc.
Method for making TPV-containing articles includes extrusion molding. However, since the rheology behaviors of TPVs differ from each other, in the extrusion of cured thermoplastics and thermoplastic elastomer compositions some undesired phenomena occurs, for example, an accumulation of material often appears at the surface of the die, which is often referred to as die “drool” or die “mustache”, and the phenomena of edge tear, silver line etc. Additionally, in a co-extrusion process of TPV and a thermoplastic material, due to difference of rheology behavior of multiple materials, it is even easy to generate unwanted phenomena. Further, when a target profile has an irregular shape or dimension, it is very difficult to achieve an excellent shape performance of extruded article. The shape and more specifically, the consistency of the shape, imparted to the molten TPV as it passes through the extruder die is dependent on not only the smoothness of the die, but also the balance of flow of extrudate. One way to control the shape and dimension of extruded article and avoid mainly relies on the controlling of the rheology behaviors of thermoplastic vulcanizate during the extrusion process.
It is desirable to provide a die suitable for extrusion or co-extrusion molding of TPV-contained article, which can effectively control and balance the flow of extrudate of different materials so as to produce an article with good shape performance and reduce occurrence of undesired phenomena during extrusion.
In addition, shaping the extruded article usually needs cooling. Since different materials have their own shaping behaviors, the shaping of a article made of two or more materials including a TPV, in particular with an irregular shape, become difficult. Thus, it is also desirable to provide a sizer during the cooling process to control the shaping of extruded article so as to achieve an excellent shape performance of cooled article.